if ( int(log($v1)/log(2))  == int(log($v2)/log(2)) ) { #match }

##</code><code>##

$ perl -e 'for my $i (1..63) {if(int(log(2**$i-1)/log(2)) != $i-1) {print "$i\n"}}'
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63